In conventional dump trucks, raising of the dump body is initiated by a manually movable lever which is connected to the spool of the hydraulic valve. When the spool is moved from its "neutral" position to its "raise" position, hydraulic fluid is pumped into the hydraulic cylinder to raise the dump body. As the dump body approaches its uppermost position, it exerts a pull on a cable connected between the dump body and the valve spool to shift the valve from its "raise" position back to its "neutral" position and automatically terminate raising of the dump body.
The dump body remains locked in its raised position until the valve spool is shifted from its "neutral" position to its "lower" position, at which time the dump body begins lowering and continues lowering as long as the valve spool remains in its "lower" position, until the dump body has been fully lowered. Lowering of the dump body is normally initiated by manually moving the control lever, but in arrangements as heretofore used lowering can also be inadvertently initiated if someone or something bumps into the cable which is connected between the dump body and the valve spool. The force applied to the cable moves the spool from its "neutral" position to its "lower" position and initiates lowering of the dump body. Moreover, after the dump body begins to lower, it will continue its downward travel even if the pressure on the cable is released. To stop the lowering action, the operator must go to the control lever, which is usually mounted in the cab, and manually move the control lever to its "neutral" position. Therefore, if the lowering action is inadvertently initiated by a person working under the raised dump body, there is an undesirable situation, since he has no way, within reach, of stopping the lowering action.
In the past, an attempt has been made to eliminate the above noted danger by use of a rigid sheath to protect most of the exposed portion of the cable from inadvertent contact. However, a short length of the cable adjacent its connection with the dump body must be exposed, so that the danger still exists for a person working around the rear of the dump body adjacent to said exposed portion.